1. Field of the Invention
This invention relates to an electronic blackboard system capable of making hardcopy of information written on the blackboard.
2. Description of the Prior Art
In recent years, various kinds of equipment have been developed in the rapid progress of office automation. One such piece of equipment is an electronic blackboard in which information written with an implement for drawing, such as a felt-tip pen or the like, on the black surface of a flexible sheet attached to the blackboard body during a conference or meeting is read out through an image sensor or an image pickup device constructed of CCD (Charge Coupled Device) as the flexible sheet is wound up at a constant rate. The read-out information may be recorded by a printer and kept in the form of hardcopy.
Referring to FIGS. 1 and 2, there are shown front and plan views, respectively, of a typical arrangement of a prior electronic blackboard. In the drawings, reference number 1 denotes a flexible sheet on which information can be written, which may be moved and rolled in a manner similar to film in a camera; number 2 designates a fluorescent lamp uniformly illuminating the surface of the sheet 1 along the longitudinal direction of the lamp; number 3 denotes a mirror disposed so as to direct the light reflected by the surface of the sheet 1 to a predetermined position; number 4 denotes a lens fixed at a predetermined position; number 5 denotes a CCD image sensor aligned with the lens 4; number 6 denotes a buffer memory storing the image data sensed by the image sensor; number 7 denotes a hardcopying machine such as a printer; and number 8 denotes an apparatus for winding and rewinding the sheet 1.
With such an arrangement, the winding/rewinding apparatus 8 rolls up the sheet 1 at a constant rate in the direction designated by arrow A after some information has been written thereon. As the sheet 1 is rolled up, the fluorescent lamp 2 illuminates the periphery of the rolled sheet 1, and the light reflected therefrom is directed by the mirror 3 to the image pickup device 5 through the lens 4 as shown in FIG. 2. Thus the image of the written information on the sheet 1 is focused onto the CCD image sensor by the lens 4, where the image is converted into a corresponding electrical signal.
It must be noted that the CCD image sensor 5 is a one-dimensional sensing means picking up an optical image as a series of lines. Therefore, the image data of all the information written on the sheet 1 is obtained by scanning each sensing element of the device 5 at a constant rate to pick up a linear image as the sheet is moved at a predetermined rate in the direction denoted by arrow A.
This image data of the information written on the sheet 1 is temporarily stored in the buffer memory 6 and then printed out by the hardcopying machine 7 in the form of hardcopy.
In the aforementioned electronic blackboard system of the prior art, since the sheet on which the information is written must be rolled up in order to read out the information, it is necessary to rewind the sheet when the blackboard is to be used for writing new information thereon. In particular, when the blackboard is used by different people in succession, the sheet must be wound and rewound every time it is used. Consequently, this prior art system is complicated in both its mechanism and its operation.
In addition, the sheet on which the information is written must be flexible because of the necessity of winding and rewinding it, and it is therefore undesirable in that a rigid board cannot be used to write on.